1. Field of the Invention
The present invention relates to terpene amino alcohols or their pharmacologically acceptable esters or salts, and medicinal uses thereof as antiallergic agents and agents for improving cerebral function.
2. Description of the Prior Art
The living body shows various defense responses to a bacterial or viral infection or to an invading heterologous protein or drug. By these immune reactions is maintained the biological integrity of the living body. However, all immune reactions are not favorable to the living body but some reactions known as allergic reactions, are harmful to the body. At the site where allergic inflammation occurs, an antigen-antibody reaction occurs on the surface of mast cells or basophils, resulting in degranulation followed by the liberation or release of chemical transmitters such as histamine, serotonin, SRS-A, ECF-A and prostaglandin. These chemical transmitters act on many vascular systems to evoke symptoms of acute circulatory insufficiency, such as hypotension, feeble pulse, disturbance of consciousness, skin pallor, cyanosis and cold sweating, respiratory symptoms such as edema glottidis, airway constriction, wheeze due to increased mucus secretion and dyspnea. In addition, they cause gastrointestinal symptoms, such as abdominal pain, borborygmus, diarrhea and vomiting, and cutaneous symptoms such as urticaria, and in severe cases, death from shock. Studies have been conducted on compounds which inhibit the release of chemical transmitters, and consequently, disodium cromoglicate, tranilast, ketotifen, etc. have been found to act on the double lipid layer of cell membrane to decrease its fluidity and stabilize the cell membrane, thereby inhibiting release of chemical transmitters from the cell surface, and have come into use as antiallergic drugs. Terpene compounds are known to have a stabilizing activity of cell membrane, and iproheptine hydrochloride, a terpene amine, has been used as an antiallergic agent in injectable form.
The above-mentioned disodium cromoglicate does not produce an antiallergic effect when administered by the oral route, which is the most convenient route of administration. Tranilast causes cystitis-like symptoms such as hematuria, pyuria and dysuria. Ketotifen is a drug of the delayed effect type, i.e. a drug whose antiallergic effect manifests itself only after about 4-6 weeks, and moreover, it causes side effects such as drowsiness. Thus, each of these inhibitors of the release of chemical transmitter has some or other undesirable features. Iproheptine hydrochloride is known to have side effects such as drowsiness and nausea. Under the circumstances, there is awaited an improved antiallergic drug that is low in toxicity with few side effects and administrable orally on a long-term basis.
With the recent increase in the number of elderly people, various geriatric diseases have come into prominence and a need for effective countermeasures has been keenly felt. Particularly, measures against senile dementia are considered to be of great importance and much research and development work has been in progress. Recently, agents for improving cerebral circulation and metabolism such as calcium hopantenate and dihydroergotoxine mesilate have been clinically used and certain nootropic drugs such as pramiracetam have also been developed.
The above-mentioned agents for improving cerebral circulation and metabolism and nootropic agents are not sufficiently effective and some of them are toxicologically undesirable. Therefore, the development of a safe drug having an excellent activity of improving cerebral function is awaited.
It is an object of the present invention to provide novel pharmacologically active compounds.
It is another object of the present invention to provide novel compounds which display excellent and sustained antiallergic activity and are safe.
It is a further object of the present invention to provide novel compounds which are readily transferred into the brain to exhibit excellent effects of improving cerebral function and are safe.
It is still another object of the present invention to provide medicinal or pharmaceutical uses of said compounds as antiallergic agents or agents for improving cerebral function.
These objects as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description.